Apparatus for the sharpening of cutters



A. 26, 1947'. E. MALAGUTI APPARATUS FOR THE SHARPENING OF CUTTEESOriginal Filed Aug. 2,1943

3 Sheets-Sheet l fzwezuor 3 :70 Mazda Aug. 26, 1947. E. MALAGUTIAPPARATUS FOR THE SHARPENING OF CUTTERS Original Filed Aug. 2, 1945 sSheets-Sheet 2 72 vendor 5w #144,460

keep in toolinventor sharpened. it""diilll loe 'iorrners'ituationnieans'alt'-tohroduction, while the latter situati'onn'ecessari-ly hieansinoreas'e'd of angle cutters Patented Aug. 26, 1947 STATES PATENT :OFJFJI'CE 25426363 ai im ith' rcs' i oit'riicsiilini hm NG 6F CUTTERIS'Eifo Melanin, We'iiesiey, 1viass.- Su hstitiited for application SerialNo. l469;9,

August 2, 1943. 'This application file'd July "31,

This "application ijs a"sulostitute' for myahhlidw tion Serial No.f496';989,"'fi'led August'2, 1e43,

The "present invention relates to the grinding of rbtary'cutters"'andmore '-pamcu1er1y, bm not exclusively; to devices for supporting"andg'auging angle type cutters js'o that *their teeth may be properlysh'arpened by {grinding operations performed on tlieir'iateral'edges.

The sharpening or 111111 angle cutters resents a serious machine shopproblem, and hitherto the only "practicable "solution "so far -'--asreal accuracy" is cohc'e'rn'ed' has bento returndull "cutters 'to f themanufacturer {for "sharpening. 3' But the difficultY-Withthis-procedureisthat considercutter "leavesa machine shop :until it is returnedsharpened; and as afre'sult' the-shop must either "stop" cuttingoperations piformed' b'y amt-particular cutter funtil--it' is*returned', or elsemust of sParesSo-thatffshafp t-ters'ofgiven-characteristics 'a1'e"- always= on harm tlil ii-le hther cuttershaying the "same characteristics areawayheing nee-apparent that -theattempt their *owrrprocedure here is'l to mount utter on -an arbor whichis s'u'pported at'its' opposite ends by the der'; clairnp a suitabletooth'rest centers 1 of a *grin V that all the' cutter 'teth grinder:tableso that ertical plane of theerinding surface at fiche half theincluded angle of But a nu'iiilfler fis atte iS -the condition OFWearGOf the ta-ble-s'ettin "-relatitely laree'nuinber 1 and with witothe'sameposition 2 is a matter of well known machine shopexperie'nce-thatdi'fferent -Wor-kmen-Wi11'in fact give a table differentangular settings although each attempts to make thesettin'g at theprecise. angle intended. But even if a satisfactory tablesetting--is'-achieved; thereremains-the necessity of -'provicling an agle of relief so that;each ground tooth edge dvi llhavecleararrce. LWhere thestructure i of the g'rinder its'elf is I such 1 that ;;one .endof the centers-supporting head and .tail stocks *rriay-be shimmedflthisprocedure is followed to pr'oide a forward- *tdther-cuttehiand SL512;consequence cause the g-r inding surface to: cut back on- *the tth andthus provide olearance. ":But where the head and tailstdckswanmotbeithus slinfinid, the alternativezprocedure iis .one whichcan do no more than merely :approaclr accuracy.

niost -angle cutter have'tth'eir teeth radially 'till loe ppa'r'ent thatwith; suchsa cutter nt d as above .described butnot tipped, thegrindertable setat atde'sired angle, "no tooth 1 clearance Twill be :providedwhen 1 the under or radial surfacecofiai toothlies {in ahoriz' tal-plane, i. e.,. int aiplan'e :pa'rallelto: that of i i table anw at T90i-to1 theigrindingasurface.

" consequence, it' is. rthe practicea toadrop the tooth t'o be' 'grouncisoi ithatiits; undemor; radial surface i igularly disposed dotmwardlyfrom said hori- -zon tal plane-:tibut 2 while *this :practice,grprovides cleairianceyitirnecessarily:causes; a departure from theintn'ded einclude'd :ang1e,';;and-- While 1 the am'ount ofzdenantureiamayn-he f-veryegreat ifthe c'utter ipositionedcarelesslmithe best-operatives candooimoresthanr-producezanrangularity'which oifiithe'iltrueangularityaibyi asimuch as; from -seven: to:fifteerilminutes. For:coarse-work this .aber'ratlonemaydoe :harmlessibut-ior precise -work-'s?aloerrati'orr:rme'ans rej ects.

he obj ect iofst-he represent invention; also to 10b" te:thei-rlifiiculties set forth-i above, and this'obiiiect'riselolrievedihxproviding a cutter-supporting and-toothagafigingconstructionavhich renders'it zunnec'essairy for-1a :shop ztoasend anglecutters out --torbe5ssharpened-and? yetmakes cpossible the ac- -45scurateli-"zangular adi'spositioneof, the; cutter teeth iwi'tharespect1-:to-- a1? grinding: surface while providineraiclearancewhichrdoesinot:cause=departure sirfornithe inten'ded included angle.

7 :.-Toitheziaccompiishment 101f. Ethis= objectaandof sfi0=iothers whichwill appear: hereinafter; the zvarious feat-ures 'of "theipresentinvention-res-ide'in certain constructions, combinations,andvarrangeeme'nts of; parts; "Fall-fully, described hereinaftersandethenrset forth inrthegappendedtclaims of iniriiportant factori'th'e element since it?-!55""ventiom:which. 1clai;ms possess advantageswhich will be readily apparent to those skilled in the art.

The various features of the present invention will be readily understoodfrom reading this specification in the light of the accompanyingdrawings, which drawings illustrate the best physical embodiment of theinvention at present known to the inventor and in which:

Fig. 1 is a view in front elevation of the cutter holder;

Fig. 2 is a view in right side elevation of the cutter holder;

Fig. 3 is a detail elevation view of the rear of the cutter holder,taken along the line 33 of Fig.

Fig. 4 is a detail view in right sectional elevation of the cutterholder, taken along the line -4 of Fig. 1;

Fig. 5 is a view in plan of the gauge plate used for positioning theholder on a grinder table in angular position with respect to a grindingsurface;

Fig. 6 is a view in elevation of the gauge plate, viewed from the smallend;

Fig. 7 is a view in perspective of the gauge plate;

Fig. 8 is a view in plan showing the cutter holder and gauge plate on agrinder table with the parts in position for the performance of agrinding operation upon a lateral edge of an angle cutter tooth;

ing a lateral edge of an angle cutter tooth; and,

Fig. 12 is a view in front elevation of a substitute spring finger usedwhen grinding the outer end of an angle cutter tooth.

Referring to the drawings, the cutter holder is provided with a baseportion (Figs. 1-2 and 8-9) from which there upwardly and forwardlyrises an extension 2| surmounted by a central post 22 (Figs. 1-4 and8),v these parts being shown integral merely for illustrative purposes.a

For convenience in manufacture, the rear surface of the base, extension,and post lie in a forwardly tipped plane, and the under surface of thebase 20 also lies'in a plane, being undercut from side to side and fromfront to rear, as indicated at 23 and 2 (Figs. 1-2), respectively, tominimize the over-all surface area to be machined to produce the plane.As will be more fully taken up infra, the forward tipping of theextension 2! and. the post 22 functions in part to provide the grindingclearance referred to in the preamble to this specification, and whilethis tipping may be at any desired or suitable angle, the particularangularity shown (Figs. 1-2 and 9) between the bottom surface of thebase 26 and the coplanar rear surfaces of the base, extension 2|, andpost 22 is 10. The front surface 25 of the base '20 is a verticalmachined surface, being at 90 to the bottom surface of the base, and thebase right and left side surfaces 26 and 21, respectively, are likewisemachined surfaces, being parallel and also at 90 to the bottom surfaceof the base 23 and its front surface 25. r

The function of the above-described structure is to provide a supportconstruction'on which an angle cutter may be rotatably. mounted so thatwardly, into the cutter keyway ii).

the lateral edges of its individual teeth may be successively ground. Tothis end (Fig. 4), the upper portion of the post 22 is provided with acylindrical passage 23 Which has a longitudinal axis located at 99 tothe planar rear surface of the post and lying in a vertical plane whichis to the plane of the vertical base surface 25. The cylindrical passage23 receives the reduced cylindrical barrel portion 23 of an adapter 35,while forwardly the adapter 39 is provided with an enlarged cylindricalportion 3! the rear face of which abuts the front face of the post 22,and forwardly of the cylindrical portion 3i the adapter 39 is providedwith a reduced cylindrical portion 32. The adapter is secured to thepost 22 by means of a set screw 33 which extends downwardly through thetop of the post into a depression 3 formed in the barrel 29, and from apoint slightly forward of the rear face of the post 22 the barrel 29 isprovided with a rearwardly extending reduced cylindrical portion 35which slidably receives a cylindrical cover 36.

The forward reduced cylindrical portion 32 of the adapter functions toreceive rotatabiy an angle cutter 3? (Figs, 1-3 and-8) herein shownmerely for illustrative purposes as being of the double angle type andhaving twenty-two radially cut teeth 38 adapted to cut a V-groove orthread. As is Well understood, the cutter S? has the usual central hubpassage 39 (Fig. 4) and keyway iii) by which it may be mounted in amachine tool, and in the mounting of the cutter on the adapter 3d thecutter passage 39 fits slidably over the adapter reduced portion 32 withthe rear face of the cutter hub engaging the front face of the adaptercylindrical portion 3 i, as shown in Fig. 4.

In order to removably secure the cutter 3? to the adapter reducedportion 32 and to effect rotation of the cutter on the holder, theadapter 30 is provided with a cylindrical passage ii (Fig. 4) which iscoaxial with the post passage 28 and which rotatably receives a shaft 2provided forwardly with a reduced portion 43 and with a squared frontenlargement or button 4% having preferably rounded corners and a flatrear face at substantially 90 to the axis of the shaft '52. Abuttingflatwise the front face of the hub of the cutter 37 is a washer 55(Figs. 1-2, 4 and 8) which is provided with a radial slot 56 in whichthe reduced portion 43 of the shaft 42 is received and with a pin tilwhich extends rear- The front face of. the washer 35 is countersunk toprovide a depression 48 having parallel sides which are spaced apartsubstantially the width of the button t l so that it may benon-rotatably received in the depression. Rearwardly the shaft .2 isprovided with a reduced threaded portion 49 which is received by theforward reduced portion 50 of a shaft 5! terminating rearwardly in ahand wheel 52, and interposed between the rear face of the adapterreduced portion 35 and the shoulder 53 formed by the junction of theshaft 5! andits forward reduced portion Ell is a spring 54 coiled aboutthe reduced portions 35 and 5t and located within the cylindrical cover35. The shaft'El is slidably received by the rear portion of the cover36, and forwardly the cover fits into the post passage 28 in abutmentwith therear annular face of the adapter barrel 29, the cover 36 beingslotted at its forward end, as indicated at 55 (Figs. .2, 3 and 8) toinsure this fit.

By reason of the above-described structure the cutterB'l is removablyand rotatably rnounted on the post 22 and therefore ,on the cutter eg-eases holder as a whole. Since the adapter 38 is fast in the passage28, the spring 54 exerts a rearward pressure against the shaft shoulder53, and since the shaft i is threaded to the shaft G2 the pressure ofthe spring 54 serves to hold the button id in the washer depression 48and as a consequence press the washer 45 against the cutter 31 so thatthe latter engages the front face of the cylindrical portion 3! of theadapter 30. In View of'the reception of the button 4 5 in the washerdepression 48, it will be seen that when the hand wheel 52 is rotatedthe washer 45 necessarily rotates with it, and since the washer pin llfits in the cutter keyway it, the cutter itself necessarily rotatesabout the axis of the shaft 52 when the hand wheel 52 is turned. As aconsequence it will be seen that by rotation of the hand wheel 52 theteeth 38 of the cutter 31 may be successively brought to a position orstation for the performance of a grinding operation upon them, and itwill also be seen that since the axis of rotation of the shaft 42 and ofthe cutter 31 is at 90 to the planar rear surface of the post 22, saidrotational axis is forwardly and downwardly tipped from the vertical.

Referring now to angle cutters in general, they are of either the singleangle or double angle type, this second type being the one illustratedat 3'! (Figs. 1-4 and 8). The included angle of each tooth in stocksizes is usually either 45 or 60 for the single angle type and 45, 60 or90 for the double angle type, with the angle being equally disposed oneach side of a center plane in this latter case and providing cuttingedges on both sides of each tooth. The double angle cutter 31 shown inthe drawings has a 60 included angle, for illustrative purposes only. Asingle angle cutter may be either right hand or left hand, dependingupon the intended direction of rotation during cutting, while righthan'dedness and left handedness of the double angle type are provided bysimply reversing the mounting of the cutter in a machine. A furtherpoint about angle cutters, whether of the single angle or double angletype, is that their teeth are usually radially cut, by which there ismeant that the under surface of each tooth (see Figs. 1 and 3, forexample) lies in a plane which is radial of the cutter.

In view of the angularity of the lateral edges of the teeth of anglecutters, it will be apparent that in order for a given tooth edge to belocated in proper relation to a grinding surface so as to permit edgesharpening at the proper angle, the cutter as a whole mustbe angularlydisposed to the grinding surface at one half the inclined angle of thecutter teeth. From this it follows that the onlytooth edge which agrinding surface can touch is that tooth edge which is nearest thegrinding surface, and where the grinding surface is'in'a vertical plane,-for example, that particular tooth edge must be horizontal if theincluded angle of the tooth edge is to be preserved duringgrind- 'ing"and not changed. If rtherewere no need of providing the teeth with anangle of relief to give them cutting clearance, it will be apparent thatacutter could be mounted in avertical plane disposed at the'proper angleto a vertical grinding surface, with the teeth brought successively to apositi'onin which the under or radial surface of ea'ch liesin ahorizontal plane. But. since a clear ance angle'ofrelief must beprovidedif the'c'utter is to function after losing ground, the under orradial surface .of each cutter toothmust not liein a'horizontal planewhen the grindingsurface is I in a vertical plane, although thehorizontal locale tion of each cutter tooth edge must be maim tained. Inorderto achieve this result with the present invention, there iscontemplated the emloyment of tooth rest constructions and also meansfor gauging the position of the tooth rests to insure that eachparticular cutter tooth edge is horizonal while being ground,although-the under or radial surface of that'tooth is nothorizontal.

To the first ,of these ends the front :of theupper part of the extension2! and of the lower part of the post 22 is provided with a recess .55.(Fig. 4) in which there is held by means of a screw 51 a transverseplate 58 (Figs. l-4 and .8).Whl0h extends beyond the opposite sides ofthe extension 2! and is provided with a forward. shelf :59 having amachined upper surface. The she1f.59 forms a support for base members 60and BI which are slidable along the shelf at opposite sides of itscenter and are adjustably held in position by means of screws '62 and.63, respectively,

' extending forwardly intothe base members through respective'slots 6Gand formed inthe plate 58. The base member 61! is providedwith an upperportion 60 which is angularly disposed so as to extend inwardly andrearwardly inthe direction of the post 22, and the base member El isprovided with an upper portion i3? which is correspondingly angularlydisposed in the direction of the post 22. Mounted on the base upperportion ea by means of a screw 68 is an upwardly extending tooth restelement comprising a spring finger fie (Figs. 1-3, 8, and 11), andmounted on the base upper portion 61 by means of a screw H3 is anupwardly extending tooth rest element comprising a spring finger "Hidentical in constructionwith the finger $9. With reference to Figs. 3and 4, the member portions 55 and :61 are forwardly tipped so that thespring fingers 69 and H carried thereby are themselves forwardly tipped,and as shown best in Fig. 11 the top surface of the finger'59 is fiatand is at to'the major axis'of the finger, while the lower end of thefinger is provided with an opening 12 through which the shank of thescrew $8 passes and which is appreciably larger than the shank so thatthe finger 59 may be adjusted vertically on the member portion 65. Thespring finger H has an identical top surface and lower openingconstruction. It is the function of the spring finger 69 to locate thecutter teeth 38 successively so'that each tooth edge facing the.grinding surface may be ground when the cutter 31 is mounted on theholder construction in such position that its downward cutting directionof rotation is clockwise (viewing Fig. 1). Since it is necessary thateach particular tooth edge be horizontal when the grinding surface isvertical if the tooth edge is to be ground at the proper angle, theheight of the top surface of the finger 69 is at such level as to makethis edge horizontal location possible, and by reason of the forwardtipping of the finger 69 it will be seen (Fig. 2) that the top surfaceof the fingerlies under and forms an abutment for the under or radialsurface of each cutter tooth. The finger E9 being of spring material,its :top will snap under the successive tooth radial surfaces as thehandwheel 52 is rotated counterclockwise (viewing Fig. 1), and by reversingthe pressure on the hand wheel each cutter tooth 38 may be manually heldin abutment with the top of the finger 69.

--In--order to gauge the position ofthe spring finger--69, i. e, inorderto insurethat its topsurface will be in such location that the frontedge of each tooth 38 when abutting the finger top surface ishorizontal, the present invention contemplates a gauge construction bythe use of which the finger 69 may be properly located independently ofthe cutter 31 and in its absence from the holder. To this end the sideof the post 22 opposite the spring finger 69 is provided with a recess13 having an upper shoulder 14 which is at 90 to the rear surface of thepost 22 and which is located at the level of the rotational axis of theshaft 42 so that this axis lies in the plane of the shoulder M, i. e.,so that a vertical plane through the rotational axis of the shaft 42 isintersected by the plane of the shoulder 14 along a line which is itselfthe rotational axis of the shaft 42. Mounted in the recess l3 by meansof a screw 15 is the vertical leg of a 90 angle member 16 the other legof which is outstanding and has a machined top surface 11 which iscoplanar with the surface of the shoulder 14. By reason of thisconstruction the rotational axis of the shaft 42 lies in the plane ofthe angle member top surface H and as a consequence this top surfacecomprises a gauge surface which is a fixed and constant part of theholder construction.

In using this top surface H as a gauge, a workman loosens the screw 68holding the spring finger 69 in position and lays a rule on the surfacell with a portion of the rule extending over the finger 69. The fingeris thereupon moved vertically until its top surface touches theoverhanging rule portion, after which the screw 68 is tightened tomaintain the finger 69 in the position thus gauged. This gaugingoperation is accomplished while there is no cutter 31 mounted on theadapter 39, but if a cutter is there present, this same gaugingoperation for the finger 69 may be performed by first temporarilyloosening the screw 52 and sliding the base member 60 outwardly alongthe shelf 59, after which the screw 68 is loosened, a rule is laid onthe gauge surface H, the finger 69 adjusted vertically as abovedescribed, and the screw 68 then tightened, the base member 6!]thereafter being moved inwardly along the shelf 59 until the top surfaceof the finger 69 is properly located transversely so as to be abuttablewith the under or radial surface of each cutter tooth 33. Either ofthese procedures may also be followed to test a mounted spring fingerfor wear of its top r surface.

But whether the gauging of the spring finger 69 be performed in eitherof the two situations above described, it willbe seen that when a cutter3'! is mounted on the holder the fact that the teeth 38 are radially cutcauses their under or radial surfaces successively to lie in the planeof the gauge surface it when abutting the top surface of the springfinger 69 and as a consequence the front edge of each cutter tooth solocated is horizontal even though the cutter as a whole is tippedforwardly.

In view of the fact that the teeth of the cutter 31 are radially cut itwill be seen that when the "cutter is mounted on the holder for rotationin a clockwise (Fig. 1) downward cutting direction, the spring finger iiis inoperative since the radial surfaces of the teeth 38 to the left ofthe vertical center 0f the post 22 are upwardly directed at variousangles. When, however, the position of the cutter Si is reversed on theholder so that the cutter is mounted for rotation in a counter-clockwise(Fig. l) downward cutting direction, the spring finger ii becomesoperative and the spring ,jfinger 69 becomes inoperative, it beingapparent .ventionally shown,

8 that the purpose of thus reversin the position of the cutter 3'! is tobring forward, or opposite to the grinding surface, those tooth edgeswhich are on the side of the cutter away from th grinding sur face andhence not ground during the tooth gauging operation of the spring finger69.

The height of the top surface of the spring finger H is at the samelevel as that of the top surface of the finger E9, and to gauge thefinger H to achieve this result the side of the post 22 opposite thespring finger ii is provided with a recess 18 (Fig. 3) having anabutment shoulder 19, these parts corresponding in form and location tothe recess 73 and its shoulder M, respectively, and there being mountedin the recess by means of a screw 89 the vertical leg of a 90 anglemember the other leg of which is outstanding and has a machined topsurface 82 corresponding in location and form to the top surface ll ofthe angle member 76. By reason of this construction the gauging surfaces82 and T? are coplanar, the surface 82 is a fixed or constant part ofthe holder construction, and the position of the spring finger H may begauged by use of a rule lyin on the gauging surface 82 in the samemanner as above described for gauging the location of the spring finger69 from the gauging surface l'l'.

Three points in particular about the holder construction as so fardescribed are to be noted. The first point is that by reason of the topsurfaces of the spring fingers 59 and "H being in the plane of thecoplanar gauging surfaces Ti and 82, the edges of the radially cut teeth38 opposite a vertical grinding surface will be successively horizontalwhen their under or radial surfaces are successively brought intengagement with the top surface of the finger 69 or the finger H, as thecase may be. Th second point is that since the axis of rotation of thecutter 3? lies in the plane of the under or radial surface of eachcutter tooth regardless of its location, and since the axis of rotationof the cutter 3? is forwardl and downwardly tipped at 10 from thevertical in the embodiment of the invention illustrated in the drawings,when the under or radial surface of a tooth engages a spring finger heor H, as the case may be, that tooth surface will itself be forwardlyand downwardly tipped at 19 although the edge of that surface oppositethe grinding surface remains horizontal. As a consequence, although theedge of each. cutter tooth is ground with a 10 angle to give clearance,the intended angularity of the cutting edge of each tooth is maintained,i, e., remains one half the included angle. The third point is thatsince the base front surface 25 is vertical and lies in a plane whichintersects at a vertical plane in which there lies the rotational axisof the shaft 62 and of the cutter 3?, the front edge of each cuttertooth 38, when its under or radial surface is engaged with a finger 69or H, is disposed angularl to the plane of the vertical base face 25 atan angle which is one half the included angle of each tooth. Where thatineluded angle is 60 for example, as above referred to, the front edgeof each tooth when located as stated is thus angularly disposed at 30.tothe vertical plane of the base front surface 25.

V The present invention contemplates that the cutter holder, with itsspring fingers 69 and il and its gauging surfaces 71 and 82, be as aunit locatable on and removable from thetable of a grinder. In Fig. 8elements of a grinder are concomprising a saucer-type grinding wheel 83mounted ona driven shaft 86 and provided with a vertical grindingsurface 9 85; a horizontal grinder table 86,; and a vertical plate 61which is secured to the front of the table 86 by means of bolts-83 andextends above the upper surface of the table with its inner surface in avertical plane to provide an abutment. For illustrative purpose only'thetable 86 is to be considered as of the magnetic-type, and by means ofthe usual adjusting mechanisms (not shown) associated with grinderconstructions, the table 86 is adjustable vertically with respect to thewheel 83, is locatable at a zero setting so that the inner verticalsurface of the plate 81 .is in a plane parallel to the vertical grindingsurface 85,

is movable along a path parallel to the plane of;

desired angle with respect to the grinding surface 85 and that whencurrent is supplied to the table magnetic elements (not shown) theholder construction will be secured to the table so that the cutter tlis held in a desired position of angularity with respect to the grindingsurface 85.

In order to gauge the location of the cutter 3? with respect to thegrinding surface '85 when the holder construction rests on the table8.6, i. e., in order to insure that the front edge of a'cutter tooth 3%abutting the top surface of a spring linger 69 or H, as the case may be,is parallel with the plane of the grinding surface 85, the presentinvention contemplates the use of a precision gauge plate 89 (Figs. 5-8)cooperating with the holder base vertical face 25 and with the innervertical surface of the table abutment plate 817 to obviate thenecessity of eye adjustment of table angularity, with the consequentgrinding aberration referred to in the preamble to this specifica-,

tion and which it is the principal object of the present invention toprevent.

With particular reference to Figs. 5-7, the gauge plate 89 has top andbottom.machined parallel surfaces 95 and 9! respectivelveither of whichis adapted to rest flatwise on the table 85 as indicated in 'Fig. 8.Atone side the plate 89 is provided with machined surface portions 92which lie in a plane at 90 to the upper and lower surfaces '99 and 9tand'which' are relieved by a depression 53 to minimize the chance oferror in machining. At another side the plate 89 is provided with othersurface portions 94 which are machined and also lie in a plane at 90 tothe upper and lower surfaces 99 and 9t and which are relieved by adepression. 85 to minimize the chance of error in machining. The planeof the surfaces $12 and the plane of the surfaces '94 are disposed toeach other at one half the included angle of an angle cutter, and sincethe'included an e of the cut er 3'! illustrated is 60, the an ularitv ofthe planes of the surfaces 92 and 94 is shownlas 30.

cut shortthereof by a surface 95, andthie plate The planes of thesurfaces 92 and 94 preferably do not converge to n edge but are 89 t oother surfaces. one of these being a surface 9'! which is at 90 to thetop and bottom surfaces and 9! and also to the adjacent surface portion9 5, and the other of these surfaces being a surface 98 connecting thesurface 9'! with the adjacent machined surfaceportion 92. Furadjacentsurface portion 94 at 90 thereto to form an abutment lip lfll, andpassages I82 of various sizes formed through the thickness of the plate89' to decrease its weight. Preferably each edge portion of the platetop and bottom surfaces 96 and 9! is bevelled, as indicated in Figs.5-8, and the height of the lip i0! is less than the vertical thickness(Fig. 6) of the plate 8% so as to extend. outwardlybetween the planes ofthe surfaces 59 and 9!.

In using the gauge plate 39 to position the holder construction, andtherefore the cutter 38 mounted thereon, on the table 88 (Fig. 8) sothat the cutter teeth may be properly ground, the gauge plate is placedfiatwise on the table with the lip till to the right (viewing Fig. 8)and with the coplanar machined surfaces 92 in abutment with the innervertical face of the table abutment plate 8?, the table 86 being at zerosetting so that the plane of this plate 81 is parallel with the grindingsurface 85. Thereafter the base 213 of the holder is placed on thetablewith its base front surface 25 abutting the coplanar machined surfaces94 of the plate 89 and with the side. 2.! (viewing Fig. 8) of the base20 in abutment with the plate lip It] I In this position the holder basefront surface 25 is, without the necessity of eye adjustment or of an uar adjustment of the table 86 with respect to the grindingsurface 85,angularly disposed 3.0 (viewing Fig. 8) to the inner surface of theplate El and to the vertical grinding surface 85, and as a, consequencethe front edge of the particular cutter tooth 38 resting on the topsurface of the spring finger 69 is parallel with the vertical grindingsurface 85, it being borne in mind that 30 is one half the includedangle of the illustrated cutter teeth and that the particular toothfront edge in question is angularly disposed 30 tothe vertical frontface 25 of the base 253. With the holder and the plate 89 thuspositioned, the table 86 is moved toward the saucer wheel 83 near enoughso that a suitable portion of the grinding surface may be in a positionto engage properly thefront edge of'the tooth 38 resting on the finger6.9, and thereafter the table 85 is magnetized and is then movedlinearly or is reciprocated so that the grinding surface 8.5 engages thefront edge of said cutter tooth and grinds it. The parallelism of thegrinding surface 85 and of the front edge of the to'oth to be groundinsures thatthe desired tooth edge angularity is maintained duringgrinding nd is not destroyed, and the forward tipping of the cutter 3'!as a whole, as explained above, insures that the tooth edge is groundwith clearance. By reason of this arrangement the edges of all the teeth33 on one side of the cutter 31 ma be successively ground, the teethbeing successively brought into abutment with the top surface of thefinger 69 by rotating the hand Wheel 52*su'ccessive1y clockwise (viewingFig. 8) and then reversing the direction of pressure on the hand wheelto maintain each tooth 38 en'- gaged with the top surface of the springfinger 69 while the front edge of each tooth i being ground. i

When the lateral tooth edges on one side of the 'cutter'3l have all beenground, the hand wheel 52 is pushed forward against the resistance ofthe spring 54, after which the washer 45 and the cutter'31 are removedso that the latter may be turned ove and mounted on the adapter withthose tooth edges forward which were formerly disposed away from thegrinding surface 85.

Thereafter the washer 45 is replaced and pressure on the hand wheel '52released to complete the mounting of the cutter 3'! in reversed positionon the holder, whereupon the gauge plate 89 is turned over to cause theli l9l to be at the left, the angle of the surfaces 92 and 94 to divergeto the left (viewing Fig. 8), and the base surfaces 25 and 25 to belocated in abutment with the surfaces 94 and the lip Illl, respectively,while the gauge plate surfaces 92 abut the inner surface of the tableplate 81. Thus relocated, the holder base surface 25 is angularlydisposed 30 to the left (viewing Fig. 8), and since the direction ofcutting rotation of the cutter 31 is now clockwise (viewing Fig. 8), thespring finger H is operative and the finger 69 is inoperative, androtating the hand wheel 52 incrementally counter-clockwise and thenreversing the direction of pressure on it serves to bring the cutterteeth 38 successively into engagement with the top surface of the springfinger ll, whereupon the grinding of the now front edges of the teethmay be performed successively as explained above. With further referenceto the lip Illl, it will be apparent that by reason of the abutment itaffords for the holder base sides 2! and 26, as the case may be,depending whether the holder base is turned angularly as shown in Fig. 8or is in a reverse position of angularity while the cutter teethabutting the top surface of the finger H are being ground, the holder asa whole and therefore the cutter 31 are properly located with respect tothe grinding surface 85 so that the position of the table 86 need not beadjustedto effect proper grinding depth when the positions of the gaugeplate 89 and of the holder construction are reversed from the Fig. 8locations to those described above.

The holder construction as a whole illustrated in Figs. 1-4 and 8provides a grinding clearance of 10. If it be desired, however, to havea different degree of clearance, means may be provided to increase ordecrease this particular 10 angularity. To this end a detachable baseplate I93 (Figs. 9-10) may be supplied having a planar machined topsurface I94 relieved by a side to side undercutting I05 and a front torear undercutting (not shown) corresponding to the undercuttings 23 and24, respectively, of the bottom surface of the base 20, and the baseplate I93 may also be provided with a planar machined under surface I06undercut as indicated at I01 and I08 in correspondence with theundercutting f the top surface I94. The top and bottom surfaces IM and196 are shown in Fig. 9 disposed to each other at an angle of and itwill be noted that this angularity diverges forwardly, i. e., to theleft, viewing Fig. 9. With this construction the 10 forward tipping ofthe planar rear face of the base 20, extension 2|, and post 22 withrespect to the under surface of the base 29 is reduced by 5, and as aesult the rotational axis of the shaft 42 (Fig. 4) and therefore that ofthe cutter 31 is forwardly and downwardly tipped at only 5 from thevertical so that the angle of relief to give clearance to each groundtooth edge is only 5. The plate I93 is removably secured to tom surfaceof the base 20 of the holder construc tion; and when the plate 193 isassembled with the base 20 the plate surface H2 lies in a plane which isintersected at 90 by a vertical plane in which there lies the rotationalaxis of the shaft 42 and of the cutter 31. The angularity of the platesurfaces I94 and I96 is shown as being 5 merely for disclosure purposes,and it will be understood that by varying this angularity in otherplates of corresponding construction the degree of clearance for eachground tooth edge may likewise be varied.

As stated above, the cutter 3'! is shown merely for illustrativepurposes as having pointed teeth, i. e., teeth adapted to cut a V-threador groove. But in cutting threads or grooves of the U. S. Standard type,or of any other type having a fiat root, the teeth of the cutter usedare not pointed as shown but are cut off flat across their outer ends.The width of this fiat is usually a definite fraction of the pitch ofthe thread or groove, and as a consequence it will be seen that when thelateral edges of the teeth of a cutter of such type are ground tosharpen them, the width of the flat is somewhat decreased, making itnecessary that the fiat ends be ground to restore to them the width theyshould have.

This grinding off the ends of the teeth may be accomplished with thepresent invention by dispensing with the gauge plate 89 and bysubstituting a spring finger H5 (Fig. 12) for the spring finger 99, forexample. Explaining this in detail, the finger H5 has the same generalshape as the finger 69 and has a lower opening I I6 correspondthe base29 by means of screws H19 (only one of ing to the opening 12, but thefinger H5 is somewhat shorter than the finger 69 and has a top surfacewhich is not a 90 to the major axis of the finger but is insteadangularly disposed downwardly to the right. By reason of this construction a cutter tooth does not have its radial or under surface coplanarwith the gauging surface H when the tooth engages the top of the fingerI I5, and instead the tooth is dropped down somewhat along its rotativepath. From this it follows that when a cutter tooth front edge isengaged by a grinding surface that is parallel therewith, the portion ofthe tooth extending upwardly and away from its front edge will not beground in a plane at 90 to the under or radial surface of the tooth butwill instead be ground in a plane which is less than 90 to said under orradial surface. As a consequence, the front cutting edge of the tooth isprovided with clearance.

In using the illustrated embodiment of the present invention toaccomplish this result with a spring finger H5 substituted on the basemember portion 66 for the finger 69, the holder is placed on the table86 with the base side surface 26 engaging the inner surface of the tableplate 81. By reason of this arrangement the front edge of the cuttertooth resting on the finger H5 is parallel with the grinding surface andmovement of the table 86 as above described in grinding the lateraledges of the teeth effects the grinding with clearance of the front edgeof each tooth, the cutter being incrementally rotated to effect thefront edge grinding of all the teeth. The degree of clearance providedby the shortened tooth H5 may be any found suitable or desiraible forthe particular cutter to be ground, and except for insuring that the topof the tooth finger I I5 is below the plane of the gauge surface 11, nogauging of the vertical location of the top of the finger H5 isnecessary since there is not involved in grinding the outer ends of theteeth teeth, the combination with a support provided on at least oneside with a fixed gauging surface lying in a plane, said support beingadapted to have a toothed cutter rotatably mounted on the front thereofin such location that upon rotation of said cutter the radial surface ofeach cutter tooth may lie in said plane but is spaced from said fixedgauging surface, of a tooth rest base mounted on the support andprovided with a tooth rest having a surface adapted, upon rotation ofthe cutter, to engage the radial surface of each tooth; said tooth restbeing movably mount-ed on its base so that the rest may be moved tocause its said surface to lie in said plane, and the mount ing of saidtooth rest base being a slidable one transversely of the front of thesupport to accommodate cutters of different diameters, and said fixedgauging surface having sufiicient area so that an element having astraight edge or a planiform surface may lie on said fixed gaugingsurface and bridge the space between it and the tooth-engaging surfaceof the tooth rest for con tact with said tooth rest surface so that itlies in said plane upon said movement of the tooth rest.

6. Structure such as set forth in claim 5, characterized by the factthat the suport, including its gauging surface, the tooth rest base, andthe tooth rest are as a unit locatable on and removable from the tableof a grinder.

7. In a holder for a cutter having radially cut teeth, the combinationwith a support provided with a fixed gauging surface lying in a plane,said support being adapted to have a toothed cutter rotatably mountedthereon in such location that upon rotation of said cutter the radialsurface of each cutter tooth may lie in said plane but is spaced fromsaid fixed gauging surface, of a tooth rest base mounted on the supportand provided with a tooth rest having a surface adapted, upon rotationof the cutter, to engage the radial surface of each cutter tooth; saidtooth rest being movably mounted on its base so that the rest may bemoved to cause its said surface to lie in said plane, said tooth restbase being mounted on the support for movement; to any one-of aplurality of positions thereon to accommodate cutters of differentdiameters, and said fixed gauging surface having sufficient area so thatan element having a straight edge or a planiform surface may lie on saidfixed gauging surface and bridge the space between it and thetooth-engaging surface of the tooth rest for contact with said toothrest surface so that it lies in said plane upon said movement of thetooth rest.

8. Structure such as set forth in claim 7, characterized by the factthat the support, including its gauging surface, the tooth rest base,and the tooth rest are as a unit locatable on and removable from thetable of a grinder.

9. In a holder for a cutter having radially cut teeth, the combinationwith a support having a fixed gauging surface lying in a plane, androtatable means for mounting a toothed cutter in spaced relation to saidfixed gauging surface but in such location that the axis of rotation ofsaid mounting mean lies in said plane, whereby upon rotation of saidmounting means the radial sur-- face of each cutter tooth may lie insaid plane, of a tooth rest provided with a surface adapted, uponrotation of the cutter, to engage the radial surface of each tooth; saidtooth rest being movably mounted on the support so that the rest may bemoved to cause its said surface to lie in said plane, and said fixedgauging surface having sufiicient area so that an element having astraight edge or a planiform surface may lie on said fixed gaugingsurface and bridge the space between it and the tooth-engaging surfaceof the tooth rest for contact with said tooth rest surface so that itlies in said plane upon said movement of the tooth rest.

10. In a holder for a cutter having radially cut teeth, the combinationwith a support havin a fixed gauging surface lying in a plane, androtatable means for mountnig a toothed cutter in spaced relation to saidfixed gauging surface but in such location that the axis of rotation ofsaid mounting means lies in said plane, whereby upon rotation of saidmounting means the radial surface of each cutter tooth may lie in saidplane, of a tooth rest base mounted on the support and provided with atooth rest having a surface adapted, upon rotation of the cutter, toengage the radial surface of each cutter tooth; said tooth rest beingmovably mounted on its base so that the rest may be moved to cause itssaid surface to lie in said plane, said tooth rest base being mounted onthe support for movement to any one of a plurality of positions thereonto accommodate cutters of different diameters, and said fixed gaugingsurface having sufiicient area so that an element having a straight edgeor a planiform surface may lie on said fixed gauging surface and bridgethe space between it and the tooth-engaging surface of the tooth restfor contact with said tooth rest surface so that it lies in said planeupon said movement of the tooth rest.

11. In a holder for a cutter having radially cut teeth, the combinationwith a support having a fixed gauging surface lying in a plane, androtatable means for mounting a toothed cutter in spaced relation to saidfixed gauging surface but in such location that the axis of rotation ofsaid mounting means lies in said plane, whereby upon rotation of saidmounting means the radial surface of each cutter tooth may lie in saidplane, of a tooth rest base mounted on the support and provided with atooth rest having a surface adapted, upon rotation of the cutter, toengage the radial surface of each cutter tooth; said tooth rest beingmovably mounted on its base so that the rest may be moved to cause itssaid surface to lie in said plane, said tooth rest base being slidablymounted on the support to accommodate cutters of different diameters,and said fixed gauging surface having sufficient area so that an elementhaving a straight edge or a planiform surface may lie on said fixedgauging surface and bridge the space between it and the tooth-engagingsurface of the tooth rest for contact With said tooth rest surface sothat it lies in said plane upon said movement of the tooth rest.

12. In a holder for a cutter having radially cut teeth, the combinationWith a support provided on at least one side with a fixed gaugingsurface lyin in a plane, and rotatable means for mounting a toothedcutter on the support in spaced relation to said fixed gauging surfacebut in such location that the axis of rotation of said mounting meanslies in said plane, whereby upon rotation of said mounting means theradial surface of each cutter tooth may lie in said plane, of a toothrest base mounted on the support and provided with a tooth rest having asurface adapted, upon rotation of the cutter, to engage the radialsurface of each cutter tooth; said tooth rest being movably mounted onits base so that the rest may be moved to cause its said surface to liein said plane, the mounting of said tooth rest base being one formovement transversely of the front of the support to accommodate cuttersof different diameters, and said fixed gauging surface having sufiicientarea so that an element having a straight edge or a planiform surfacemay lie on said fixed gauging surface and bridge the space between itand the tooth-engaging surface of the tooth rest for contact with saidtooth rest surface so that it lies in said plane upon said movement ofthe tooth rest.

13. In a holder for a cutter having radially cut teeth, the combinationwith a support provided with a member having a fixed position thereonand also having a fixed gauging surface lying in a plane, said supportbeing adapted to have a toothed cutter rotatably mounted thereon in such1ocation that upon rotation of the cutter the radial surface of eachcutter tooth may lie in said plane .but is spaced from said fixedgauging surface, of a tooth rest provided with a surface adapted, uponrotation of the cutter, to engage the radial surface of each tooth; saidtooth rest being movably mounted on the support so that the rest may bemoved to cause its said surface to lie in said plane, and said fixedgauging surface having sufiicient area so that an element having astraight edge or a planiform surface may lie on said fixed gaugingsurface and bridge the space between it and the tooth-engaging surfaceof..the tooth rest so that movement of the tooth rest to cause saidtooth-engaging surface to engage said straight edge or planiform surfaceresults in said tooth-engaging surface lying in the plane of said fixedgauging surface.

14. In a holder for a cutter having radially cut teeth, the combinationwith a support provided with a member having a fixed position thereonand also having a fixed gauging surface lying in a plane, said supportbeing adapted to have a toothed cutter rotatably mounted thereon in suchlocation that upon rotation of the cutter the radial surface of eachcutter tooth may lie in said plane but is spaced from said fixed gaugingsurface, of a tooth rest base mounted on the support and provided with atooth rest having a surface adapted, upon rotation of the cutter, toengage the radial surface of each tooth; said tooth rest being movablymounted on its base so that the rest may be moved to cause its saidsurface to lie in said plane, said fixed gauging surface havingsufficient area so that an element having a straight edge or a planiformsurface may lie on said fixed gauging surface and bridge the spacebetween it and the tooth-engaging surface of the tooth rest so thatmovement of the tooth rest to cause said tooth-engaging surface toengage said straight edge or planiform surfac results in saidtooth-engaging surface lying in the plane of said fixed gauging surface,and said tooth rest base being movably mounted on the support toaccommodate cutters of different diameters.

15. In a holder for a cutter having radially cut teeth, the combinationwith a support provided with a fixed gauging surface lying in a plane so18 disposed that the lower surface of a cutter tooth and the top surfaceof a tooth rest may lie in said plane, said support being adapted tohave a toothed cutter rotatably mounted thereon in such location thatupon rotation of said cutter the radial surface of each cutter tooth maybe a lower surface lying in said plane but is spaced from said fixedgauging surface, of an upwardly extending tooth rest provided with a topsurface adapted, upon rotation of the cutter, to engage the radialsurface of each tooth; said tooth rest being movably mounted on thesupport so that the rest may be moved to cause its said top surface tolie in said plane, and said fixed gauging surface having sufficient areaso that an element having a straight edge or a planiform surface may lieon said fixed gauging surface and bridge the space between it and thetooth-engaging top surface of the tooth rest for contact with said topsurface so that it lies in said plane upon said movement of the toothrest.

16. In a holder for a cutter having radially cut teeth, the combinationwith a support provided with a fixed gauging surface lying in a plane sodisposed that the lower surface of a cutter tooth and the top surface ofa tooth rest may lie in said plane, said support being adapted to have atoothed cutter rotatably mounted thereon in such location that uponrotation of said cutter the radial surface of each cutter tooth may be alower surface lying in said plane but is spaced from said fixed gaugingsurface, of a tooth rest base mounted on the support and provided withan upwardly extending tooth rest having a top surface adapted, uponrotation of the cutter, to engage the radial surface of each tooth; saidtooth rest being movably mounted on its base so that the rest may bmoved to cause its said top surface to lie in said plane, said toothrest base being slidably mounted on the support to accommodate cuttersof different diameters, and said fixed gauging surface having sufficientarea so that an element having a straight edge or a planiform surfacemay lie on said fixed gauging surface and bridge the space between itand the tooth-engaging top surface of the tooth rest for contact withsaid top surface so that it lies in said plane upon said movement of thetooth rest.

EVO MALAGUTI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Ringzelli July 3,

